SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e2b6f309dae24e905cd8a368abde53907406c96b92cf26e43f40d8bd400b7949' 
  AND token = 'xXse8cPhaxLMo4J3nO1EjJpNyXt/7GRiB/oG/j1gUKg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}